Deadly gems: is gem mining a blessing or curse in Kenya?

The film ‘Blood Diamonds’ provides a glimpse into the atrocities that conflict over minerals can bring to a nation. In this case, greed for yellow diamonds in Sierra Leone created political and economic strife leading to the exploitation and inhuman treatment of the local population. Hence if gem mining is not carefully managed the repercussions can in many cases be deadly.

Gems and precious stones can command high prices in the marketplace and as with fashions, they are considered to be rare and novel until another unique variety is discovered or becomes fashionable. This means that the price and value of gems can be constantly varying, which does not provide a stable enviroment for mining investment. Gem mining can be a touchy subject, especially within the environmental community. This form of gem mining can either be a blessing or a curse, depending on the checks and balances in place during the process. It seems strange to see mineral-rich nations produce priceless gems only to keep their populations in abject poverty and avoid dealing with other challenges such as matters relating to public health. There is a push and pull dynamic between the fundamental questions: is mining necessary? Is mining evil (or is it those humans that exploit others who are evil)? and can mining provide an economic boost to the source areas?

Photo 1

Photo 1: Range of garnet gems with varying colours and cuts.

Through my work I have seen communities adversely affected by mining through loss of property rights and even deaths. Adverse effects can occur when miners feel unfairly compensated for their manual and technical input. This can generate an uprising and halt the mining; any economic benefits from the mining are then lost due to the socio-economic issues raised during the unrest.

In Kenya (which is my motherland) mining has been active for decades without the benefits derived from gem production being spread from the producer to the general public. Moreover, the geology of certain rare gems is poorly reported. Gems such as Tsavorite and Tanzanite are only understood within limited of mining and academic circles. Tsavorite, also known as the green garnet, is a gem with a very high market value but its geological origin remains a scientific curiousity for gemologists and mineral enthusiasts. It belongs to the family of garnet minerals, which vary in their chemistry, principal ion compositions and colour.

Green garnet is used as a gemstone in place of emerald due to its higher refractive index and dispersion. Other types of garnet are also used as indicator minerals in exploration for diamonds due to their presence (sometimes together with diamonds) in kimberlite rocks. More common garnets are used as abrasives due to their hardness, which is close to that of feldspar and quartz.

The market value of Tsavorite is about $860/carat. The colour of Tsavorite varies from dark green (which is considered highly desirable) to light green (market value about $105/carat), with shades of yellow and grey.

Tsavorite is found in quartz veins (Tanzania) or nodules (Kenya) and consists mainly of calcium, aluminium and silica. It has a dark green colour due to the presence of chroium and vanadium. The only Tsavorite nodules exploited to date are from the Davis Mine, which is located in Mwatate, south-eastern Kenya. This is where I carried out my research into this unique host environment for green garnet. The process of data collection and interpretation involved interactions between academics, researchers, miners, and mine owners, as well as government geologists who play a key role in Kenyan mining policy. Kenya is well endowed with minerals such as titanium, gold, mineral fuels, and gemstones. It also has considerable potential for gem production if the extraction and marketing processes and techniques are properly designed and controlled.

Photo 2: Tsavorite porphyroblasts, together with rough and faceted gems from the Tsavo area, Kenya. Stones courtesy of Genson Micheni Musa, Tsavolite Co. Ltd (Photo: V. Pardieu/Gübelin Gem Lab, 2007).

Photo 2: Tsavorite porphyroblasts, together with rough and faceted gems from the Tsavo area, Kenya. Stones courtesy of Genson Micheni Musa, Tsavolite Co. Ltd (Photo: V. Pardieu/Gübelin Gem Lab, 2007).

Resources with very high returns can either be a source of great conflict, or stimulate socio-economic development. I believe that mining policy needs to focus more on achieving a more equitable distribution of the wealth that it generates. My work simply highlights one of the rare gems that could improve the economic and social dynamics of their source areas, which tend to be remote, underdeveloped and underprivileged areas compared to the cities that thrive on the benefits of mining.

My research has involved exploration of the Davis Mine on foot. Litho-stratigraphic columns have been prepared describing the rock types, their physical dimensions, and the sampling locations. The Tsavorites are hosted in calc-silicate rocks within graphitic gneiss. Geochemical analyses of samples have revealed calcium, aluminum and silica enrichment in both the host rock and the Tsavorite nodules. Rare earth element patterns showed the europium anomaly expected from upper continental crust rocks, while the Tsavorite nodules yielded hafnium and tellurium anomalies. All the geochemical samples had lanthanum and lutetium contents which further supports the idea of an upper crustal environment for their formation. Petrographic analysis revealed metamorphosed sediments of graphitic gneiss, metapegmatites and graphitic schist, with opaque inclusions of garnet and iron oxide minerals. The mineralogy indicates that the original sediments underwent pro-grade metamorphism, which resulted in the formation of Tsavorite in calc-silicate pockets.

It is time for the government to place fair measures in place because Kenya needs to avoid a ‘conflict mineral’ situation similar to that in the Congo and Sierra Leone. Mining needs to be carried out in an environmentally friendly way, with subsequent rehabilitation of former agricultural areas. With these points in mind, the extraction of Kenyan minerals should be carried out by Kenyan workers, for the benefit of both local Kenyans and the whole of Kenya. This can only happen if we have the right legal framework and environmental protection acts implemented.




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Abigail Wamunyu is a geologist who has worked on the geochemistry and mineralogy of gems in her academic research and fieldwork. Previously she was involved in environmental geo-hazards, a field she would like to incorporate with possibly climate change studies in future graduate work.

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